Biological samples are often obtained by researchers and clinicians in the field of histopathology. Samples are collected for diagnostic evaluation to determine the presence of a certain disease and to determine an appropriate treatment for the disease. Common diagnostic processes for diseases include histological and cytological diagnosis. For example, tumors are typically examined for histological and cytological abnormalities.
Biological samples are also obtained for molecular diagnostic evaluation. In recent years, nucleic acid analysis and studies have become common place in research for the treatment of numerous diseases. An essential requirement for accurate nucleic acid qualitative and quantitative analysis is the presence of high quality and intact nucleic acids. For example, intact nucleic acid is necessary for RT-PCR, Northern blot hybridization and nuclease protection assays analysis of nucleic acid expressions.
Biological samples can be obtained from various sources and by various processes. Numerous devices exist that are designed to remove a small amount of sample from an organ or other specimen. For example, small samples can be obtained by surgical processes such as by use of a scalpel or a device similar to a punch to extract core fragments of tissue. Another device for performing a biopsy uses a needle device that can extract single cells, small cell clumps and tissue fragments.
Generally, it is preferable to prepare a biological sample for subsequent analysis immediately after being extracted from the patient or source to obtain the most accurate results possible. Numerous molecular, cellular and morphological changes can occur in the sample during collection and transport, which can affect the final results. For example, nucleic acid in a biological sample can undergo numerous changes, such as up regulation, down regulation and degradation. The rate of these changes can be affected by temperature.
The analysis of a biological sample at the time of collection is often impossible or not practical. Therefore, it is necessary to store the sample under controlled conditions to prevent or inhibit degradation of the sample and to retain the integrity of the results of the analysis. Biological samples are typically stored in a container with a suitable fixative reagent. A typical fixative reagent is 10% formalin. Other fixatives include water miscible alcohols, ethanol/acetone mixtures, and ethanol/acetic acid mixtures. Ammonium sulfate solutions have also been used as disclosed in U.S. Pat. No. 6,204,375 to Lader, which is hereby incorporated by reference in its entirety. The containers with the biological sample in the fixative reagent can then be sent to a pathology laboratory or other destination for analysis.
Proper handling of the biological sample is essential for accurate analysis, and particularly for nucleic acid quantitative and qualitative evaluation. The biological samples require an effective amount of the fixative reagent to preserve the sample. In addition, some reagents are required to completely cover the sample with the reagent to ensure effective preservation. Typically, the biological samples are simply placed in a small container for storage. The biological samples which can be very small can be difficult to locate and recover from the container.
To obtain high quality test results, early stabilization of specimens may be required. For example, biological samples can be quick frozen by various methods, such as with liquid nitrogen or dry ice, as known in the art. The samples are usually preserved in formaldehyde and alcohol based solutions and chaotropic salt.
Quick freezing of biological samples can be effective in stabilizing cellular and molecular characteristics. Quick freezing is not always convenient or available. Typically, the collection location and processing laboratory are separated in location and time, which create an impediment to stabilization.
The prior methods for collecting, storing, transporting and stabilizing biological samples have known limitations. Accordingly, there is a continuing need in the industry for an improved method and container for collecting, transporting, storing and processing biological samples.